ahh I understand. warming up gets you a lot lower fuel economy DURING the warm up. so a shorter trip means that warm up period is much larger percentage wise so the colder temps will hit this "warm up" period more and since its a larger percentage of your total trip the effect is visible in the numbers. So I won't see as much a gain if any from a engine heater on my FE as for example he might?

Yes. I drove my wife's car to Las Vegas from the Bay Area last month, and gassed up when we got there. That night, we drove to another part of town to see a show. The next day, I drove home. The night I drove to the casino, I put 13 miles on the car at 17 mpg. It took me the next 450 miles to bring my mileage up over 40 mpg the next day, because I'd used nearly a full gallon to go 13 miles on a cold engine in city conditions.

__________________
Darrell

Boycotting Exxon since 1989, BP since 2010
Have you ever noticed that anybody driving slower than you is an idiot, and anyone going faster than you is a maniac? George Carlin
Mean Green Toaster Machine
49.5 mpg avg over 53,000 miles. 176% of '08 EPA
Best flat drive 94.5 mpg for 10.1 mi
Longest tank 1033 km (642 mi) on 10.56 gal = 60.8 mpg

You name me a car capable of getting 40 mpg, and I'll show you how to get 13 (actually 17) mpg out of it.

The car I did it with is my wife's '06 AT Hyundai Elantra. We drove at night, had to run the heater and lights, and didn't hit many stoplights on green. We also had to drive the Strip on a weekend, with its stop and go traffic. Even FASing at lights, I could only get 17 mpg that night.

When I lived in Alaska, I could only expect 5 mpg in the winter with my 4X4 Scout. Winter driving kills fuel economy.

I actually averaged >41 mpg over ~1000 miles on that trip. It just took all day to overcome the effects of that first 13 miles at 17 mpg. When you're doing short commutes every day, you never overcome the cold starts.

__________________
Darrell

Boycotting Exxon since 1989, BP since 2010
Have you ever noticed that anybody driving slower than you is an idiot, and anyone going faster than you is a maniac? George Carlin
Mean Green Toaster Machine
49.5 mpg avg over 53,000 miles. 176% of '08 EPA
Best flat drive 94.5 mpg for 10.1 mi
Longest tank 1033 km (642 mi) on 10.56 gal = 60.8 mpg

That was trip and tank average fuel economy for the 13 miles. It's not uncommon for an AT econocar to stay under 20 mpg for the first few miles when it's started up. My wife's car doesn't have a fe readout. I had a Scangauge plugged into it.

__________________
Darrell

Boycotting Exxon since 1989, BP since 2010
Have you ever noticed that anybody driving slower than you is an idiot, and anyone going faster than you is a maniac? George Carlin
Mean Green Toaster Machine
49.5 mpg avg over 53,000 miles. 176% of '08 EPA
Best flat drive 94.5 mpg for 10.1 mi
Longest tank 1033 km (642 mi) on 10.56 gal = 60.8 mpg